Glutathione (GSH) functions as a major antioxidant within cells and plays an important role in various pathophysiologies associated with oxidative stress. The glutathione concentration in cancer cells is also said to be maintained higher than in normal cells, and it is thought to be one cause of treatment resistance to radiation and anticancer drugs.
Therefore, measuring the intracellular glutathione concentration is important for clarifying the participation of oxidative stress in various pathologies. Furthermore, estimating the glutathione concentration of cancer cells can serve as a highly useful tool in actual practice to make it possible to predict treatment resistance and the like.
Methods for measuring the glutathione concentration using a reagent that changes fluorescence intensity and emission intensity before and after reaction with glutathione are consequently being researched. However, existing glutathione measurement reagents and methods reported in the literature (such as Non-patent Reference 1) do not permit measurement in live cells since the cells must be disrupted for reaction with the intracellular glutathione. There are also reports of glutathione-sensitive probes that can be applied to living cells, but all have poor quantitativeness and problems remain in that measurement over time is not possible because an irreversible reaction with glutathione is utilized.